java Map常用方法封装

 

java Map常用方法封装

CreationTime--2018年7月16日15点59分

Author:Marydon

1.准备工作

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import org.apache.log4j.Logger;

/**
 * Map数据处理工具类
 * @explain
 * @author Marydon
 * @creationTime 2018年7月9日上午9:17:37
 * @version 1.0
 * @since
 * @email marydon20170307@163.com
 */
public class MapUtils {

    private static Logger log = Logger.getLogger(MapUtils.class);
}

2.无序Map转换成有序Map

/**
 * 将无序Map转换成有序Map
 * @explain 将参数按照第一个字符的键值 ASCII 码递增排序（字母升序排序），如果遇到相同字符则按照第二个字符的键值 ASCII 码递增排序，
 *          以此类推通过SortedMap可以实现
 * @param paramsMap
 * @return Map 按ASCII码升序排列
 */
public static Map<String, Object> toSortedMap(Map<String, Object> paramsMap) {
    // 用于存储接收到的key:value，并按key以ASCII码进行升序排列组合
    SortedMap<String, Object> data = new TreeMap<String, Object>();
    // 获取Map对象中的键值对对象
    Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
    Entry<String, Object> entry = null;
    String key = "";
    Object value = null;
    // 遍历paramsMap数据，添加到SortedMap对象
    for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
        entry = iterator.next();
        key = entry.getKey();
        value = entry.getValue();
        data.put(key, value);
    }
    log.info("Map-->SortedMap：" + data);
    return data;
}

3.将map的value转化成String类型

/**
 * Map<String, Object>-->Map<String, String>
 * @explain 前提：value必须为String类型
 * @param paramsMap
 * @return
 * @throws Exception
 */
public static Map<String, String> toStringMap(Map<String, Object> paramsMap) throws Exception{
    Map<String, String> data = new HashMap<String, String>();
    // 获取Map对象中的键值对对象
    Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
    Entry<String, Object> entry = null;
    String key = "";
    String value = null;
    for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
        entry = iterator.next();
        key = entry.getKey();
        if (key instanceof String) {
            value = (String) entry.getValue();
            data.put(key, value);
        } else {
            log.error("Map中含有非String类型的值，对应的key=" + key);
            throw new Exception("Map中含有非String类型的值，对应的key=" + key);
        }
    }
    log.info("Map<String, Object>-->Map<String, String>：" + data);
    return data;
}

4.将map的value转化成Object类型

/**
 * Map<String, String>-->Map<String, Object>
 * @explain 将value转换成Object类型
 * @param paramsMap
 * @return
 */
public static Map<String, Object> toObjectMap(Map<String, String> paramsMap){
    Map<String, Object> data = new HashMap<String, Object>();
    // 获取Map对象中的键值对对象
    Set<Entry<String, String>> entrySet = paramsMap.entrySet();
    Entry<String, String> entry = null;
    String key = "";
    Object value = null;
    for (Iterator<Entry<String, String>> iterator = entrySet.iterator(); iterator.hasNext();) {
        entry = iterator.next();
        key = entry.getKey();
        value = entry.getValue();
        data.put(key, value);
    }
    log.info("Map<String, String>-->Map<String, Object>：" + data);
    return data;
}

5.将map的key小写转换成大写

/**
 * key 小写-->大写
 * @explain 将key改为大写
 * @param paramsMap
 * @return
 */
public static Map<String, Object> toUpperMap(Map<String, Object> paramsMap){
    Map<String, Object> data = new HashMap<String, Object>();
    // 获取Map对象中的键值对对象
    Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
    Entry<String, Object> entry = null;
    String key = "";
    Object value = null;
    for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
        entry = iterator.next();
        key = entry.getKey().toUpperCase();
        value = entry.getValue();
        data.put(key, value);
    }
    log.info("Map 小写-->大写：" + data);
    return data;
}

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